O-Aminopropyl starch was prepared by Michael addition of acrylonitrile and subsequent reduction with freshly prepared cobalt
boride and sodium borohydride. In a second approach, the aminopropyl group was introduced via Williamson etherification with
N-phthalyl-protected 3-bromo-1-propylamine. The protecting group was removed by borohydride reduction and subsequent
hydrolysis in acetic acid. The DS of all samples and the degree of reduction of the cyanoethyl groups were estimated from the
1
H NMR spectra. Total monomer composition was determined after methanolysis or hydrolysis and trimethylsilylation by GLC
and GCMS. While the regioselectivity in the thermodynamically controlled reaction was O-6O-2O-3 (50:37:13), the kinetically
controlled process showed strongly preferred O-2-etherification (up to 94%) followed by O-6- and O-3-substitution. It could be
influenced by choice of solvent (water, Me2SO) and base (NaOH, Li-dimsyl). © 2002 Elsevier Science Ltd. All rights reserved.